Farpoint Tri-Bahtinov Mask — Celestron 11" SCT (Hyperstar/Fastar)Not sure this is the right mask for your telescope? Use our Focus Mask Finder match your scope to the right Standard, Tri Bahtinov, or Hyperstar RASA mask. Custom fit Tri Bahtinov focus and collimation mask for the Celestron 11" SCT with Hyperstar Fastar capability. Drops onto the front of your telescope, gives you focus AND a collimation check from a single short exposure, and lifts off cleanly when you're done. Made in our own shop in the USA